The present invention relates to an apparatus and method for electronically controlling an engine, and in particular to an apparatus and method for electronically controlling an engine so as to prevent longitudinal oscillation of the vehicle at the time of acceleration and deceleration.
The state of a vehicle changes depending upon whether the automobile is driven at a constant speed, accelerated or decelerated. If the engine is always controlled in the same way, therefore, oscillation in the longitudinal directions i.e., running directions of the vehicle or the like is caused, and hence the driver and the passenger feel uncomfortable. In order to prevent such longitudinal oscillation and make driving comfortable, electronic engine control apparatuses for performing engine control electronically have heretofore been used.
In an example of the method of preventing the longitudinal oscillation by using this electronic engine control apparatus is described in JP-A-No. 59-231144 and JP-A-No. 60-30446, correction is performed by fuel injection at the time of deceleration. In another prevention method as described in JP-A-No. 59-93945, correction is performed by means of the ignition advance angle and the amount of fuel supply so that the torque fluctuation may become minimum when the automobile runs at an extremely low speed.
As for the method of preventing the longitudinal oscillation of a vehicle in the above described prior art, correction was performed by means of the ignition advance angle, fuel injection and the like only at the time of deceleration and at the time of extremely low speed running. Assuming now that the driving state of a vehicle is divided into three modes, i.e., acceleration mode, constant speed running mode and deceleration mode, effective correction for preventing the longitudinal oscillation of a vehicle was not performed in the acceleration mode in the prior art. Because a method of detecting the longitudinal oscillation at the time of acceleration was not generally introduced. That is to say, there was no means for detecting whether movement of a vehicle whereby the driver felt uncomfortable was being cased or not in all of the acceleration, constant speed running and deceleration modes. Further, movement of acceleration affecting the driver's comfort was not considered. There were no systems having indexes, which could be selected by each driver, interposed in control.